Plain English Meaning

A weather alert telling pilots that a large area has clouds low enough or visibility poor enough that you cannot legally or safely fly by looking outside. You will need instruments and an IFR clearance to operate in that area.

Full Definition

An AIRMET advisory issued by the National Weather Service warning of widespread instrument flight rules conditions, specifically ceilings less than 1,000 feet and/or visibility less than 3 statute miles affecting an area of at least 3,000 square miles. It also includes extensive mountain obscuration when applicable.

Context Anchor

You see AIRMET IFR during preflight weather planning before an , especially when checking whether the may require in clouds or poor visibility.